Modern Vespa

Electric ignition on my ET2 suddenly stopped working. Can hear 1 click from relay when I try ignition.

Checked voltage at battery terminals seems to be 12.5 before starting, drops when trying ignition to 8V or so (brake light dims too) and voltage unstable when revved (oscillates around 18V). Though might be battery so Tried a car battery but no success.

Replaced regulator- but no improvement.

When kick-started the indicators are flashing too fast

I was sure it was the regulator. Any advice on how to track down the problem. My thoughts are could it be an earth problem - if so where? Could the regulator I swapped in by failing too? Could it be a problem with the relay?

Grateful for advice on what to do next.

This thread is quite good for electrical advice. It certainly sounds like a rectifier issue. Usually batteries also get fried by faulty regulators. Hopefully someone with more knowledge will come along soon.

If your battery is dropping to 8v under load (as when starting), then it's toast. It should not drop below 10. Time for a new battery, sorry.

And yes, it sounds like you've got two duff regulators. Was the second one brand new?

Battery

If you connect a car battery and it's the same trouble
Change motor ignition

I have carried out more investigations.
It wont electric start start when a car battery is attached.

I followed a thread on testing electrics and connected the two thick wires from the relay together to see if it would start but not a peep.

Also with the relay short circuited and i measure no resistance between the + and -ve wires with the battery removed. Does this suggest the starter is kaput? would that also explain why the current drops when the ignition is pressed?

I cant easily get to the starter motor on my ET2 so I cant easily remove it to test it directly.

Suggestions?

Ignition motor hs

The starter motor will read as a near short circuit - the winding resistance is minimal. This is why you don't have a fuse in the way, the instantaneous inrush current just before the motor starts to turn can be up to 90A or more.

So has my starter broken if I attach the the two wires either side of the relay and the starter doesnt kick in? Also tried a car battery in case motorcycle battery dying but no luck.

How do you get the starter out on an ET2 - it seems very inaccessible.

Why are the indicators flashing quicker the more I rev the engine? As I said above I replaced the regulator but still the same problem with the voltage at the battery oscillating around 18V when i rev the engine. can earth problems cause this and if so where and how should I look for this?

Have you actually tested the battery itself? Many years ago I had a Piaggio Zfera that had similar symptoms - all down to a high resistance battery.

And yes, it could well be a poor earth (ground in the US) connection. The battery negative should be connected both to the frame of the bike and to the engine, usually on the starter motor itself, but not always.